Comment on It's not supposed to make sense...
kayzeekayzee@lemmy.blahaj.zone 4 days agoSorta! According to the Heisenberg Uncertainty Principle, there’s an upper limit to how much we can “know” about the given state of a particle. This isn’t an issue with our measurements, but a fundamental property of the universe itself. By measuring one aspect of a quantum system (for example, the momentum of a particle), we become less certain about other aspects of the system, even if we had already measured them before (such as the position of the same particle).
Brainsploosh@lemmy.world 4 days ago
Thank you for your answer!
Maybe I’m too dense, but what happens with other quantum states that aren’t position/velocity based? I’m thinking things like when we collapse spin, e.g. in entangled particles.
I’ve heard that entangled particles are “one use”, I’d assume they can be restored and possibly re-entangled, but how?
kayzeekayzee@lemmy.blahaj.zone 4 days ago
Good question! You are certainly not dense!
The position-momentum uncertainty relationship is just a specific case of a more general relationship. There are other uncertainty relationships, such as between time and energy or between two (separate/orthogonal) components of angular velocity. The relationships basically state that whenever you measure one of the two values, you are required to add uncertainty to the other.
Unfortunately, this is kinda where my knowledge on the subject starts to hit its limits. As for spin, it has a lot of effects on the energy of the system it’s involved with, so I believe the energy-time or angular momentum exclusion principles would apply there.
Krudler@lemmy.world 4 days ago
Entanglement is a fucked up concept that I’m just starting to grasp.
Parametric down sampling, say, causes particles to split, and then certain states of the resultant particles must respect conservation.
So if the source particle had no spin, but the resultant particles must have spin, one will have minus half spin and the other will have plus half spin. Equals zero, which was the total spin of the source particle. Same deal with charges.
But they are not resolved until this wishy-washy “measurement” thing comes into the picture